Skip to content

Instantly share code, notes, and snippets.

@saidimu

saidimu/iptables_rules.sh

Forked from virtualstaticvoid/iptables_rules.sh
Created January 10, 2014 03:59
Show Gist options
  • Save saidimu/8346781 to your computer and use it in GitHub Desktop.
Save saidimu/8346781 to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. @virtualstaticvoid virtualstaticvoid created this gist Jun 14, 2011.
    118 changes: 118 additions & 0 deletions iptables_rules.sh
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,118 @@
    # Modify this file accordingly for your specific requirement.
    # http://www.thegeekstuff.com
    # 1. Delete all existing rules
    iptables -F

    # 2. Set default chain policies
    iptables -P INPUT DROP
    iptables -P FORWARD DROP
    iptables -P OUTPUT DROP

    # 3. Block a specific ip-address
    #BLOCK_THIS_IP="x.x.x.x"
    #iptables -A INPUT -s "$BLOCK_THIS_IP" -j DROP

    # 4. Allow ALL incoming SSH
    iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
    iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

    # 5. Allow incoming SSH only from a specific network
    #iptables -A INPUT -i eth0 -p tcp -s 192.168.200.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

    # 6. Allow incoming HTTP
    iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
    iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT

    # Allow incoming HTTPS
    iptables -A INPUT -i eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
    iptables -A OUTPUT -o eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT

    # 7. MultiPorts (Allow incoming SSH, HTTP, and HTTPS)
    iptables -A INPUT -i eth0 -p tcp -m multiport --dports 22,80,443 -m state --state NEW,ESTABLISHED -j ACCEPT
    iptables -A OUTPUT -o eth0 -p tcp -m multiport --sports 22,80,443 -m state --state ESTABLISHED -j ACCEPT

    # 8. Allow outgoing SSH
    iptables -A OUTPUT -o eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
    iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

    # 9. Allow outgoing SSH only to a specific network
    #iptables -A OUTPUT -o eth0 -p tcp -d 192.168.101.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

    # 10. Allow outgoing HTTPS
    iptables -A OUTPUT -o eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
    iptables -A INPUT -i eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT

    # 11. Load balance incoming HTTPS traffic
    #iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 0 -j DNAT --to-destination 192.168.1.101:443
    #iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 1 -j DNAT --to-destination 192.168.1.102:443
    #iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 2 -j DNAT --to-destination 192.168.1.103:443

    # 12. Ping from inside to outside
    iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT
    iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT

    # 13. Ping from outside to inside
    iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
    iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT

    # 14. Allow loopback access
    iptables -A INPUT -i lo -j ACCEPT
    iptables -A OUTPUT -o lo -j ACCEPT

    # 15. Allow packets from internal network to reach external network.
    # if eth1 is connected to external network (internet)
    # if eth0 is connected to internal network (192.168.1.x)
    iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT

    # 16. Allow outbound DNS
    iptables -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT
    iptables -A INPUT -p udp -i eth0 --sport 53 -j ACCEPT

    # 17. Allow NIS Connections
    # rpcinfo -p | grep ypbind ; This port is 853 and 850
    #iptables -A INPUT -p tcp --dport 111 -j ACCEPT
    #iptables -A INPUT -p udp --dport 111 -j ACCEPT
    #iptables -A INPUT -p tcp --dport 853 -j ACCEPT
    #iptables -A INPUT -p udp --dport 853 -j ACCEPT
    #iptables -A INPUT -p tcp --dport 850 -j ACCEPT
    #iptables -A INPUT -p udp --dport 850 -j ACCEPT

    # 18. Allow rsync from a specific network
    #iptables -A INPUT -i eth0 -p tcp -s 192.168.101.0/24 --dport 873 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A OUTPUT -o eth0 -p tcp --sport 873 -m state --state ESTABLISHED -j ACCEPT

    # 19. Allow MySQL connection only from a specific network
    #iptables -A INPUT -i eth0 -p tcp -s 192.168.200.0/24 --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A OUTPUT -o eth0 -p tcp --sport 3306 -m state --state ESTABLISHED -j ACCEPT

    # 20. Allow Sendmail or Postfix
    iptables -A INPUT -i eth0 -p tcp --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT
    iptables -A OUTPUT -o eth0 -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT

    # 21. Allow IMAP and IMAPS
    #iptables -A INPUT -i eth0 -p tcp --dport 143 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A OUTPUT -o eth0 -p tcp --sport 143 -m state --state ESTABLISHED -j ACCEPT
    #iptables -A INPUT -i eth0 -p tcp --dport 993 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A OUTPUT -o eth0 -p tcp --sport 993 -m state --state ESTABLISHED -j ACCEPT

    # 22. Allow POP3 and POP3S
    #iptables -A INPUT -i eth0 -p tcp --dport 110 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A OUTPUT -o eth0 -p tcp --sport 110 -m state --state ESTABLISHED -j ACCEPT
    #iptables -A INPUT -i eth0 -p tcp --dport 995 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A OUTPUT -o eth0 -p tcp --sport 995 -m state --state ESTABLISHED -j ACCEPT

    # 23. Prevent DoS attack
    iptables -A INPUT -p tcp --dport 80 -m limit --limit 25/minute --limit-burst 100 -j ACCEPT

    # 24. Port forwarding 422 to 22
    #iptables -t nat -A PREROUTING -p tcp -d 192.168.102.37 --dport 422 -j DNAT --to 192.168.102.37:22
    #iptables -A INPUT -i eth0 -p tcp --dport 422 -m state --state NEW,ESTABLISHED -j ACCEPT
    #iptables -A OUTPUT -o eth0 -p tcp --sport 422 -m state --state ESTABLISHED -j ACCEPT

    # 25. Log dropped packets
    iptables -N LOGGING
    iptables -A INPUT -j LOGGING
    iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables Packet Dropped: " --log-level 7
    iptables -A LOGGING -j DROP